The battle over interracial versus racially segregated proms has roiled Southern high school life for years, but the case of gay teen Constance McMillen represents a new front in the Dixie prom wars: same-sex dates.

After Ms. McMillen, an 18-year-old senior at Itawamba Agricultural High School in Mississippi, announced she’d be wearing a tuxedo and bringing a female date, a sophomore, to the school’s April 2 dance, the school district said no way. Officials then circulated a flier saying students could not bring same-sex dates.

When McMillen and a lawyer from the American Civil Liberties Union (ACLU) gave the school district a deadline to rescind the ruling, the school board on Wednesday voted to cancel the prom rather than abide by McMillen’s wish. On Thursday, the ACLU filed a lawsuit in US district court, charging that school officials violated McMillen's free speech rights when they told her they would enforce the district's policy requiring prom dates to be of the opposite sex.

Fearing recrimination, McMillen didn't want to return to campus Thursday, and said she might have to switch schools.

"That's really messed up because the message they are sending is that if they have to let gay people go to prom that they are not going to have one," she told the Jackson Clarion-Ledger after learning of the cancellation. "A bunch of kids at school are really going to hate me for this, so in a way it's really retaliation."

McMillen did go to school Thursday, and encountered some hard feelings from classmates, but said she was standing up for herself and others in her situation. "My daddy told me that I needed to show them that I'm still proud of who I am," McMillen told The Associated Press in a telephone interview. "The fact that this will help people later on, that's what's helping me to go on."

Though school officials haven’t commented on Wednesday’s decision, earlier remarks indicate they feared McMillen's choice of date could become a disruption to the school’s educational process.

The controversy touches on the often uneasy tensions that can surround gay dating in high school.

In socially liberal parts of the country, like Los Angeles and Miami, same-sex prom dates are common. In more conservative areas, such as Utah, gay teens sometimes hold separate proms. But in Deep South towns like McMillen’s hometown of Fulton, Mississippi, some school districts simply don’t allow same-sex dating at the prom.

Still, recent events point to views on sexuality changing in the South, too. Virginia Gov. Bob McDonnell (R) on Wednesday said he’d fire state employees who discriminated against gays in the workplace.

Gay rights groups quickly hailed McMillen as a hero for standing up to conservative Southern values. McMillen herself told the Clarion-Ledger that she was inspired by Ceara Sturgis, a senior in Wesson, Miss., who last year insisted on being photographed for the yearbook in a tuxedo. Ms. Sturgis' picture never made it into the yearbook, but her stand was widely reported.

The notion that a lesbian prom date would disrupt education at Itawamba irked activists.

"Eliminating the prom … sends a message of intolerance, and a message that the school is much more interested in playing politics, rather than prioritizing the interests of their student body,” writes Michael Jones at Change.org.

Some conservative groups support the school district. One, the Liberty Counsel, an Orlando-based social policy organization, says McMillen’s gambit is part of a broader attempt to force legal recognition of same-sex couples. There is evidence of such a push: School officials in Russellville, Ala., last year reversed its “no-same-sex-dating” policy after the ACLU took the case.

"The district might be motivated by a desire to prevent the ultimate conduct that is presumptively illegal in this state," Liberty Counsel attorney Stephen Crampton told the Clarion-Ledger.

The ACLU says the decision to cancel the prom is a violation of McMillen’s constitutional rights. Mississippi is one of a few states with an antisodomy law still on the books, but a 2003 US Supreme Court decision stuck down all such state laws because they discriminate against Americans.